Ellipsometry is currently used for the measurement of film thickness, dielectric function and composition. Ellipsometry is not sufficiently sensitive to certain electrical properties of materials such as band structure, mobility, trapped charge, etc. Similarly, modulated reflectance (e.g., photoreflectance, electroreflectance, etc.) are able to measure some of these properties but are often not sensitive enough.
It is within this context that embodiments of the present invention arise.